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lib/Class/GAPI.pm  view on Meta::CPAN

		return (as_ptr($self->{$functioname})) ; # Yep even scalars are returned as pointers
	} 
	else {  # Initialize property and Return the value 
		unless (exists $self->{$functioname}) { $self->{$functioname} = undef ; } 
		return $self->{$functioname} ; 
	}
}

sub as_ptr { unless(ref $_[0]) { return \$_[0] ; } else { return $_[0] ; } } # 

sub sprout {
	my $self = shift     ; 
	my $newclass = shift ; 
	$self->{$newclass} = Class::GAPI->new() ; 
	return $self->{$newclass} ;  
}

sub clone {	# Make a recursive copy of self, provided that subordinates also have "clone" functions 
	my $self = shift         ;
	my $class = ref($self)   ;
	my $twin = $class->new() ; 
	while(my ($key, $val) = each %$self) {
		if (! ref($self->{$key})) {
			$twin->{$key} = $val ; 
		} elsif(is_blessed($self->{$key})) {
			my $block = ('$twin->{$key} = $val->clone();') ; 
			eval($block) ;
		} else {
			$twin->{$key} = $val ; # try and pass unblessed references  
		}
	} 
	return $twin    ; 
}

sub load {  # Broadcast namespace down the tree.    
	my $self = shift ; 
	my @libs = @_    ; 
	foreach (@libs) {      
		my $block = join '', ('use ', $_, ';')   ; 
		eval($block) 				     ;
	}
	while(my ($key, $val) = each %$self) {
		if (is_blessed($val)) { 
			my $block = '$val->load(@libs);'   ; 
			eval($block) 			     ;
		}
	} 
}

sub is_blessed { # Object detection.  
	my $val = shift ; 
	if (ref($val)) {
		foreach('SCALAR','ARRAY','HASH','CODE','GLOB','REF','LVALUE','IO::Handle') {
			if ($val =~ $_ ) { return 0 ; }
		}
		return 1 ; 
	} 
	return 0 ; 
}  

sub overlay {  # Convert a hash into a series of function calls.
	my $self = shift 		          ;
	return undef if  scalar(@_) % 2   ;
	my %pairs = @_ 			    ;
 
	while(my ($k, $v) = each %pairs) {
		my $block = join "", ( '$self->', $k, '(', '$v', ');' ) ;
		eval($block)          	 	    ;
		if ($@) {
			my $class = ref($self) 		    ; 
			warn ("$class is executing $block and throwing:\n $@\n XXXXXXXXXXXXXXXXXXX") ;
		}	
	} 
	return $self ; 
}

sub warn_self { # pass ($self $string) to warn ($self $string 1) to intercept warn data. 
	my $self = shift       ; 
	my $id = shift 	     ; 
	my $class = ref($self) ; 
	my $cstring = "\n$id object $self in $class" ; # Class info  
	while(my ($k, $v) = each %$self) { $cstring .= "\n  $k\-\>$v" ; }
	unless (scalar(@_)) { warn $cstring ; } 
	else { return $cstring ; } 
}

1 ;

############### CODE ENDS HERE ############################## 

=head1 NAME

Class::GAPI - Generic API, Base class with autoloaded methods, stub objects, cloning etc. 

=head1 SYNOPSIS

	package Guppy ;

	use Class::GAPI			; # All of its cool stuff 
	our @ISA = qw(Class::GAPI)	; # is now in our namespace

	our @Children = qw(Class::GAPI::Fin Class::List::Eyeballs CGI)	; # Autoconstruct Subordinates
	our @Default_Properties = qw(scaly small sushi)				; # Call at constructor time

	use strict ;
 
	sub _init { # Last stage of initialization
		  my $self = shift ; 
		  $self->fillet(1) if defined $self->{'sushi'}; # sushi exists but is undefined
     		return 1;
	}
	1 ;

	package Petstore ; 
	use Guppy        ; 
	my $pet = Guppy->new(color => 'orange', price => '.50', small => 1, -sushi => 1) ; # envoke these functions
	$pet->Eyeballs->[0] = "left"	; # Access a special list subclass
	$pet->Eyeballs->[1] = "right"	; # 
	$pet->Fin->dorsal("polkadot")	; # Access a subordinate Class::GAPI object
	$pet->Fin->tail("orange")	; #   

lib/Class/GAPI.pm  view on Meta::CPAN

this case "Foo" can be anything you like, and will correspondingly be used to create a 
sprout()ed object. Note that Class::GAPI::Foo is a a sprouted hash, while Class::List::Foo 
is a sprouted array. This is very convenient for making lists of objects. The technique below can be used 
to quickly create a variety of styles of record manager classes. 


	package Guppy::School	; 
	use Guppy		; 
	our @ISA = qw(Guppy)	; # We are derived from a Guppy, which is derived from a GAPI  
	our @Children = qw(Class::List::School) ; # $self->{'School'} is now an array

	sub doSpawn { # Add a new Guppy Object
		my $self = shift 			 ;	 
		my $fish = Guppy->new() 	 ; 
		push @{$self->School()}, $fish ; 
	}

	sub fishNet { # Get a specific Guppy object 
		my $self = shift    		 ; 
		my $n = shift       		 ; 
		my $fish = $self->School->[$n] ;
		return($fish) 	  		 ;   
	}
	1 ;

The third stage of initialization is by defining a local &_init subroutine. This gets called after everything else. So if one desires to 
do something with passed variables after the class is blessed, this is where to do it. If you call an autoloaded function here, it takes place 
after autoloaded functions from ->new(), and Default_Properties. So you do have access to data passed or processed during invokation. 

passed at invokation:  

	package Guppy		; 
	use Class::GAPI		; 
	our @ISA = (Class::GAPI);
	use strict		; 
 
	sub _init {
		my $self = shift ; 
		$self->chopchopchop() if $self->sushi() && $self->filet() ; 
	}
	1 ; 

	package PetShop ; 
	use Guppy       ; 

	my $pet = Guppy->new(-sushi => 0, -filet => undef) ; 
	my $lunch = Guppy->new(-sushi => 1, -filet => 1)   ;
 

In this case the execution of method chopchopchop would occur 
in the case of lunch but not in the case of pet. 

=head1 OTHER FUNCTIONS

Cloning is supported for Class::GAPI objects and any subordinate objects based on Class::GAPI
or that Inherit Class::GAPI. This includes Class::List objects. This is function is eval()d, so it 
will not crash if you have other stuff in their, just don't expect that other stuff copy. 

	my $twin = $pet->clone(); # Make the FDA nervous 

The overlay() function allows one to execute a block of functions by passing hash.  This is equivilant 
to what happens when constructed with new(). This is typically usefull when you want to copy a hash 
into several objects as you might in a record table:

	package Guppy::School	; 
	use Guppy		; 
	our @ISA = qw(Guppy)	; # We are derived from a Guppy, which is derived from a GAPI  
	our @Children = qw(Class::List::School) ; # $self->{'School'} is now an array

	sub doSpawn { # Add a new Guppy Object
		my $self = shift		;
		my $fish = Guppy->new(@_)	; # Pass options pairs to the new fish 
		push @{$self->School()}, $fish  ; 
	}

	sub fishGrow { # Add a block of options like so: fishGrow(2, foo => 'bar') ;  
		my $self = shift		; 
		my $n = shift			; 
		$self->School->[$n]->overlay(@_); 
		return($fish)			;   
	}
	1 ;

The warn_self() function is pretty much what it sounds like. You can call it at any level with 
a tree of nested GAPI and it will produce a table of the object as a warning. Obviously this 
handy for debugging: 

	$self->warn_self() ;
	$self->Foo->Bar->warn_self() ; 

=head1 NOTES

It is worth noting that GAPI uses a lot of eval() calls. So it is fairly slow. Also special 
care should be given to using this module in CGI because of that. You should probably 
read the code and understand how the constructor works before even considering using this 
thing in cgi code. Consider yourself warned.  

This was written on an Win32 box running cygwin and Activestate, and it works on both with Perl 5.8. 
I expect it should work with anything later than 5.6.1, but It hasn't been tested. 

Autoloaded methods tend to cause silent failure modes. Essentially typos that would have 
normally crashed perl will often just end up creating a dangling property somewhere. 
Use $self->warn_self() to take snapshots of objects if something is not getting properly 
populated. If you see two similarly named properties, you've found the culprit. 

No animals were harmed in the development of this module. 

=head1 AUTHOR

Matthew Sibley 
matt@itoperators.com

=head1 COPYRIGHT AND LICENCE

Copyright (C) 2005 Crosswire Industries Inc.  (http://www.itoperators.com) 

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself, either Perl version 5.8.6 or,
at your option, any later version of Perl 5 you may have available.

=cut